Removal of the package is not possible:
hello-world-app.postrm uses bashishms (arrays) which are not supported by
ash. The script is marked as #!/bin/sh which it shouldn't be. Also, it uses the
array for something silly, which could be replaced by using sed -i directly.

After fixing the postrm manually, the package can now be removed (via
application manager), home, statusbar and control panel icons will be gone, but
the icon in the application menu will stay.

This last bug is due to a file rename on package install and it is never
renamed back (the hello-world.desktop file) and as such, it will remain on the
device even if the package is removed.

#! /bin/sh

#Remove the desktop entries from the configuration files
home_data="hello-world-home.desktop"
sb_data="hello-world-sb.desktop"
tn_data="hello-world-tn.desktop"
path="/etc/hildon-desktop"
sed -i "/$home_data/d" $path/home.conf
sed -i "/$sb_data/d" $path/statusbar.conf
sed -i "/$tn_data/d" $path/tasknavigator.conf